Aquality analyst wants to construct a control chart for determining whether three machines, all producing the same product, are in control with regard to a particular quality variable. accordingly, he sampled four units of output from each machine, with the following results: machine measurements #1 17 15 15 17 #2 16 25 18 25 #3 23 24 23 22 what are the x-bar chart three-sigma upper and lower control limits? multiple choice 24 and 16 23.16 and 16.84 23.29 and 16.71 23.5 and 16.5 22 and 18